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compiler.h: Fix annotation macro misplacement with Clang

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When building with Clang and CONFIG_TRACE_BRANCH_PROFILING, there are a
lot of unreachable warnings, like:

  arch/x86/kernel/traps.o: warning: objtool: handle_xfd_event()+0x134: unreachable instruction

Without an input to the inline asm, 'volatile' is ignored for some
reason and Clang feels free to move the reachable() annotation away from
its intended location.

Fix that by re-adding the counter value to the inputs.

Fixes: f1069a8756 ("compiler.h: Avoid using inline asm operand modifiers")
Fixes: c199f64ff9 ("instrumentation.h: Avoid using inline asm operand modifiers")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/0417e96909b97a406323409210de7bf13df0b170.1636410380.git.jpoimboe@redhat.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: x86@kernel.org
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Miroslav Benes <mbenes@suse.cz>
This commit is contained in:
Josh Poimboeuf 2021-11-08 14:35:59 -08:00
parent cb8747b7d2
commit dcce50e6cc
2 changed files with 4 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
include/linux/compiler.h
View File

@ -121,7 +121,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
asm volatile(__stringify_label(c) ":\n\t" \
".pushsection .discard.reachable\n\t" \
".long " __stringify_label(c) "b - .\n\t" \
".popsection\n\t"); \
".popsection\n\t" : : "i" (c)); \
})
#define annotate_reachable() __annotate_reachable(__COUNTER__)
@ -129,7 +129,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
asm volatile(__stringify_label(c) ":\n\t" \
".pushsection .discard.unreachable\n\t" \
".long " __stringify_label(c) "b - .\n\t" \
".popsection\n\t"); \
".popsection\n\t" : : "i" (c)); \
})
#define annotate_unreachable() __annotate_unreachable(__COUNTER__)

4
include/linux/instrumentation.h
View File

@ -11,7 +11,7 @@
asm volatile(__stringify(c) ": nop\n\t" \
".pushsection .discard.instr_begin\n\t" \
".long " __stringify(c) "b - .\n\t" \
".popsection\n\t"); \
".popsection\n\t" : : "i" (c)); \
})
#define instrumentation_begin() __instrumentation_begin(__COUNTER__)
@ -50,7 +50,7 @@
asm volatile(__stringify(c) ": nop\n\t" \
".pushsection .discard.instr_end\n\t" \
".long " __stringify(c) "b - .\n\t" \
".popsection\n\t"); \
".popsection\n\t" : : "i" (c)); \
})
#define instrumentation_end() __instrumentation_end(__COUNTER__)
#else